Cu Core Ball, Solder Joint, Solder Paste and Formed Solder

Abstract

A Cu core ball contains a Cu ball and at least one metal layer for covering a surface of the Cu ball. The metal layer is made of at least one element selected from the group of Ni, Co, Fe and Pd. The Cu ball contains at least one element selected from a group of Fe, Ag and Ni in a total amount of 5.0 ppm by mass or more to 50.0 ppm by mass or lower, S in an amount of 0 ppm by mass or more to 1.0 ppm by mass or lower, P in an amount of 0 ppm by mass or more to less than 3.0 ppm by mass, and remainder of Cu and inevitable impurities. The Cu ball contains purity which is 99.995% by mass or higher to 99.9995% by mass or lower, and sphericity which is 0.95 or higher.

What is claimed is: 
     
         1 . A Cu core ball comprising:
 a Cu ball; and   a solder layer for covering a surface of the Cu ball,   wherein the Cu ball contains at least one element selected from a group of Fe, Ag and Ni in a total amount of 5.0 ppm by mass or more to 50.0 ppm by mass or lower, S in an amount of 0 ppm by mass or more to 1.0 ppm by mass or lower, P in an amount of 0 ppm by mass or more to less than 3.0 ppm by mass, and remainder of Cu and inevitable impurities,   wherein the Cu ball contains purity which is 99.995% by mass or higher to 99.9995% by mass or lower, and sphericity which is 0.95 or higher, and   wherein the solder layer contains Cu in an amount of 0.1% by mass or more to 3.0% by mass or lower, Bi in an amount of more than 0% by mass to 10.0% by mass or less, and remainder of Sn.   
     
     
         2 . The Cu core ball according to  claim 1  wherein the solder layer contains Cu in an amount of 0.1% by mass or more to 3.0% by mass or lower, Bi in an amount of 0.5% by mass to 5.0% by mass or less, Ag in an amount of 0% by mass or more to 4.5% by mass or less, Ni in an amount of 0% by mass or more to 0.1% by mass or less and remainder of Sn. 
     
     
         3 . The Cu core ball according to  claim 1  wherein the sphericity thereof is 0.98 or higher. 
     
     
         4 . The Cu core ball according to  claim 1  wherein the sphericity thereof is 0.99 or higher. 
     
     
         5 . The Cu core ball according to  claim 1  wherein the Cu core ball contains alpha dose which is 0.0200 cph/cm 2  or lower. 
     
     
         6 . The Cu core ball according to  claim 1  wherein the Cu core ball contains alpha dose which is 0.0010 cph/cm 2  or lower. 
     
     
         7 . The Cu core ball according to  claim 1 , further containing a metal layer which covers a surface of the Cu ball and the solder layer which covers a surface of the metal layer wherein the sphericity thereof is 0.95 or higher. 
     
     
         8 . The Cu core ball according to  claim 7  wherein the sphericity thereof is 0.98 or higher. 
     
     
         9 . The Cu core ball according to  claim 7  wherein the sphericity thereof is 0.99 or higher. 
     
     
         10 . The Cu core ball according to  claim 7  wherein the Cu core ball contains alpha dose which is 0.0200 cph/cm 2  or lower. 
     
     
         11 . The Cu core ball according to  claim 7  wherein the Cu core ball contains alpha dose which is 0.0010 cph/cm 2  or lower. 
     
     
         12 . The Cu core ball according to  claim 1  wherein the Cu ball has a diameter of 1 μm or more to 1000 μm or less. 
     
     
         13 . A solder joint using the Cu core ball according to  claim 1 . 
     
     
         14 . The solder joint according to  claim 3 , the Cu core ball further containing a metal layer which covers a surface of the Cu ball and the solder layer which covers a surface of the metal layer wherein the sphericity thereof is 0.95 or higher. 
     
     
         15 . Solder paste using the Cu core ball according to  claim 1 . 
     
     
         16 . The Solder paste according to  claim 15 , the Cu core ball further containing a metal layer which covers a surface of the Cu ball and the solder layer which covers a surface of the metal layer wherein the sphericity thereof is 0.95 or higher. 
     
     
         17 . Formed solder using the Cu core ball according to  claim 1 . 
     
     
         18 . The formed solder according to  claim 17 , the Cu core ball further containing a metal layer which covers a surface of the Cu ball and the solder layer which covers a surface of the metal layer wherein the sphericity thereof is 0.95 or higher.